Charge Line

[David Alston]

I have had two vehicles where the charging current went through the ignition swich. Bad experiences in both cases. There is always some voltage drop across a diode, so it has some disadvantage as a method for isolating the trailer battery. I would want to put a fuse in the line feeding the trailer. I've had batteries short out and cause problems and this would protect the vehicle to some degree.

[Anon 1]

[crankshaft]

Dear SteveH,

Could you spell that out for us dummies. Precisely how do you hook it up to the ignition? What wires go to what posts?

Attach a red #10 wire and a 30 amp in-line fuse to the + terminal of the battery. From the battery, the wire goes to the solenoid contactor (which will be labeled). Then the red wire goes from the solenoid contactor to the + terminal of the trailer battery (through the plug connecting it to the tow vehicle). There already should be a ground wire to the trailer for the stop/turn lights so you don't need to add another one if its there. Make sure you get a continuous duty solenoid. Starter solenoids are only rated for intermittant use and will fail prematuraly. Then find a wire in the car that is only hot when the key is on. Splice in a #12 wire from the key-on-hot wire to the coil of the solenoid. Make sure the coil is grounded and you're done. Clear as mud, right?

Here's a picture of a starter solenoid for an example. The wire from the batteries goes to the big terminals on the right and left. The key-on-hot wire goes to one of the little posts in the middle. A ground wire goes to the other little post in the middle. I can post a wiring diagram sketch if anyone wants one.
Bruce

Bruce.


Thanks for the offer of a diagram... ( I read pitchurs better than I read writeing )


You can respond e-mail wise at [email protected]

Crankshaft

[Paul W]

You will want to fuse the circuit to the trailer (wire #4) and also to ensure you prevent a dead car battery in the morning, or from 'deep cycling' your car (starting) battery, you may want to consider a Hellroaring Unit. www.hellroaring.com

From Hellroaring...
For most applications, (i.e. slide-in camper, trailer, RV's with required continuous loads under 50 amps on the auxiliary side during engine operation, etc...) consider the basic deep cycle application.   Your primary objective is to prevent your  starting battery from draining while you consume power from your house (deep cycle) battery.   (Don't be fooled by low cost battery disconnect devices as a solution.  If you try to use these, your starting battery will get deep cycled and will result in early failure.)